1. Field of the Invention
This invention relates to animal feed supplements. In one aspect, the invention relates to extruded, high-fat animal feed nuggets suitable for consumption by ruminants and other animals raised for commercial purposes. In another aspect, the invention relates to a method of making an extruded, high-fat animal feed nugget using conventional extrusion equipment. In yet another aspect, the invention relates to finished feed products of which the extruded, high-fat animal feed nugget is a components.
2. Description of the Prior Art
Fat is a desirable component of most animal diets, and the art is replete with methods of introducing it into the diets of various livestock. In addition to serving as an energy source, fat can have an impact on the quality and quantity of milk production in dairy animals and meat production of animals raised for slaughter, e.g. various ruminants, pigs, poultry and fish.
Many methods are known for introducing fat into an animal diet, and for packaging it into a convenient and useful form for handling, storage and eventual consumption. For example, Scott and Hills teach in U.S. Pat. No. 3,925,560 a method for improving the utilization of lipid materials by ruminants comprising feeding the ruminants an emulsion or emulsion product comprising homogeneous lipid bodies dispersed within an edible medium. The feed supplement can be in the form of a finely divided particulate solid, e.g. diameters of 0.01 to 5 millimeters, or may be prepared and administered as a liquid emulsion.
Sawhill teaches in U.S. Pat. No. 4,804,546 a stable, thixotropic suspension of fat in an aqueous liquid gel of a feed solution. The gel is prepared by forming a solution of sugar, protein or a mixture of both, and then incorporating ammonium phosphate into the solution followed by the addition of water, and then fat.
McAski teaches in U.S. Pat. No. 4,826,694 a feed stuff for ruminants comprising an edible, water-insoluble salt of an edible fatty acid, free fat, an excess of the salt-forming metal, and other nutritional material, such as proteinaceous meal (e.g. soybean). The feed stuff is produced as a friable product.
While the above described methods are effective for introducing fat into an animal diet, usually the most desirable method is to introduce the fat (or at least a major portion of the fat) as a component of a pellet which itself is a component of a finished feed product. However, incorporating more than four or five weight percent (wt %) of fat into the body of the pellet (or an extruded particle) is difficult and has led to the development of a specialized body of art. For example, U.S. Pat. No. 2,945,764 by Lanz and U.S. Pat. No. 3,014,800 by Guidarelli teach methods for producing dry, hard feed pellets containing fat. In both instances, relatively low amounts of fat are incorporated into the body of the pellet and the remaining fat, up to an additional 15 wt %, is applied as a coating to the pellet.
Handy in U.S. Pat. No. 3,623,885 and Skoch and Sewell in U.S. Pat. No. 4,143,169 teach a related technique for the incorporation of fat into a hard, dry animal food produced as an extruded nugget. However as reported in these teachings, incorporating more fat within the pellet or nugget results in undesirable crumbling and excessive fines, while similar amounts applied onto the surface of the pellet or nugget produces a product that is soft, friable, and has a greasy texture.